Interpretation of World War II reconnaissance photos. Aerial photos are of great value in locating systems of a certain vertical extension. The shadow of many systems is characteristic and conspicuous. As my work progressed, an iterative process resulting from the interaction between statements and ground photos, combined with the study of aerial photos from 1945 (scale 1:40.000) and 1954 (scale 1:15.000), was instrumental in the creation of a photographic interpretation database. Based on the photo interpretation it was possible to conduct a field survey of the suspected location to look for the foundation of the equipment in question. Again an interactive process had to be used. The only foundations initially known from ground photos were those of the Würzburg Riese, The Freya-Fahrstuhl and the Heinrich Peiler. Through the above method the following foundations were identified:

• Russel. • See-Elefant. • Wassermann M. • Various Freya LZ foundations. • Two types of Hans E-mess Geräte towers.

The identification of the foundations again made it possible to establish the position of electronic equipment in other sites.

A Freya A/N. I have never been able to identify this radar on an aerial photo.

Würzburg-Riese. The pattern is not very conspicuous. However in many areas the radar is

protected by barbed wire and other obstacles and there are frequently trenches around it. This creates a “cats-paw” pattern which is quite characteristic. The radar itself frequently

stands out as white “blob” from the foundation with a strong shadow from the antenna.

Freya LZ C. The same shape is created by a Dreh-Freya or Freya EGON in a Splitter Mauer.

Wassermann S.

Wassermann M 1/2. In costal areas the shadow is frequently washed out by the undulating terrain. The 3 buildings adjacent to the site are, however, very characteristic and at least in

Denmark they are always present.

Wassermann M 4.

Russel.

See-Elefant. The shadow is just discernable.

Mammut. The shadow is very massive.

Jagdschloss. Conspicuous pattern but not easily identified.

A ”heavy” Heinrich Peiler tower.

A ”light” Heinrich Peiler tower.

Hans E-Mess Gerät tower. Very thin shadow, difficult to detect.